5.6 @section: Sections Below Chapters

An @section command identifies a section within a chapter
unit, whether created with @chapter, @unnumbered, or
@appendix, following the numbering scheme of the chapter-level
command. Thus, within an @chapter chapter numbered ‘1’, the
sections are numbered ‘1.1’, ‘1.2’, etc.; within an @appendix
“chapter” labeled ‘A’, the sections are numbered ‘A.1’, ‘A.2’, etc.;
within an @unnumbered chapter, the section gets no number.
The output is underlined with ‘=’ in Info and plain text.

To make a section, write the @section command at the
beginning of a line and follow it on the same line by the section
title. For example,

@section This is a section

might produce the following in Info:

5.7 This is a section
=====================

Section titles are listed in the table of contents.

The TeX, HTML, Docbook, and XML output is all analogous to the
chapter-level output, just “one level down”; see @chapter.